Many industrial facilities employ a device commonly referred to as a PLC—short for Programmable Logic Controller. As is known, a PLC provides a microprocessor-based industrial control system. The PLC communicates with other process control components through data links. PLCs are used in process control for simple switching tasks (e.g., opening and closing a valve), PID control, complex data manipulation, arithmetic operations, timing and process and machine control, etc. For example, a PLC may be connected to sensors configured to supply temperatures, pressures, flow rates, and a variety of other numerical values related to the operational state of an industrial operation. Similarly, the PLC may also collect information on discrete values such as whether a given valve is open or closed. The PLC may be configured store this information in specific addresses, registers, or database locations.
Further, the microprocessor included in the PLC may be configured to engage in a variety of process control actions, based on the reported data. For example, a PLC may be programmed to maintain a specific temperature in a process chamber. In such a case, the PLC may perform actions to increase the temperature (e.g., close/open valves, increase fuel flowing to a combustion chamber, etc.) when the temperature falls below a specified minimum. Similarly, the PLC may perform the opposite actions to decrease the temperature when it exceeds a specified maximum.
Additionally, a PLC may be configured to respond to requests for information on what value was recorded for a given sensor at any given point in time. Such requests typically take the form of a request for a specific memory location or database value. Further, such requests must be formatted using a communications protocol “understood” by the PLC. In some cases, the ability for a PLC to speak a given communication protocol may be augmented by adding a communication card to the PLC. However, adding a communications card to the PLC frequently requires extensive PLC configuration and often a plant shutdown, which can be extremely disruptive. Further, some communication cards only provide access to limited data from a PLC device—thus this approach may simply fail, depending on what data from the PLC a plant operator desires to retrieve.